13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- 4. ODAs were only found for fatigue tests at R = -1. A reason for this may be reduced crack closure at R > 0, which has to be proven by further investigations of fracture surfaces by means of an SEM after FIB preparation of sections perpendicular to the crack surface. 5. The evaluation of the threshold values according to Döker was applied to short cracks. The results also indicate that crack closure effects may play an important role in connection with the ODA formation. Acknowledgements The authors gratefully acknowledge funding of this study by the Deutsche Forschungsgemeinschaft (DFG). References [1] C. Berger, B. Pyttel, D. Schwerdt, Beyond HCF - Is there a fatigue limit?, Materialwissenschaften und Werkstofftechnik, 39 (2008) 769-776. [2] S.X. Li, Effects of inclusions on very high cycle fatigue properties of high strength steels, Int. Mater. Rev., 57 (2012) 92-114. [3] H. Mughrabi, Fatigue, an everlasting materials problem - still en vogue, Procedia Engineering, 2 (2010) 3-26. [4] T. Sakai, Review and Prospects for Current Studies on Very High Cycle Fatigue of Metallic Materials for Machine Structural Use, International Journal of Fatigue, 3 (2009) 425-439. [5] H. Mughrabi, Specific features and mechanisms of fatigue in the ultrahigh-cycle regime, International Journal of Fatigue, 28 (2006) 1501-1508. [6] T. Sakai, M. Takeda, K. Shiozawa, Y. Ochi, M. Nakajima, T. Nakamura, N. Oguma, Experimental evidence of duplex S-N characteristic's in wide life region for high strength steels, China Higher Education Press Beijing, Beijing, 1999. [7] H.W. Höppel, L. May, M. Prell, M. Göken, Influence of grain size and precipitation state on the fatigue lives and deformation mechanisms of CP aluminium and AA6082 in the VHCF-regime, International Journal of Fatigue, 33 (2011) 10-18. [8] Q.Y. Wang, C. Bathias, N. Kawagoishi, Q. Chen, Effect of inclusion on subsurface crack initiation and gigacycle fatigue strength, International Journal of Fatigue, 24 (2002) 1269-1274. [9] Y. Murakami, S. Kodama, S. Konuma, Quantitative evaluation of effects of non-metallic inclusions on fatigue strength of high strength steels. I: Basic fatigue mechanism and evaluation of correlation between the fatigue fracture stress and the size and location of non-metallic inclusions, International Journal of Fatigue, 11 (1989) 291-298. [10] K. Shiozawa, T. Hasegawa, Y. Kashiwagi, L. Lu, Very high cycle fatigue properties of bearing steel under axial loading condition, International Journal of Fatigue, 31 (2009) 880-888. [11] T. Sakai, Y. Sato, Y. Nagano, M. Takeda, N. Oguma, Effect of stress ratio on long life fatigue behavior of high carbon chromium bearing steel under axial loading, International Journal of Fatigue, 28 (2006) 1547-1554. [12] Z. Mazur, A. Hernández-Rossette, R. García-Illescas, Investigation of the failure of the L-0 blades, Engineering Failure Analysis, 13 (2006) 1338-1350. [13] W.-Z. Wang, F.-Z. Xuan, K.-L. Zhu, S.-T. Tu, Failure analysis of the final stage blade in steam turbine, Engineering Failure Analysis, 14 (2007) 632-641. [14] Z. Mazur, R. Garcia-Illescas, J. Porcayo-Calderon, Last stage blades failure analysis of a 28 MW geothermal turbine, Engineering Failure Analysis, 16 (2009) 1020-1032. [15] Z. Mazur, R. Garcia-Illescas, J. Aguirre-Romano, N. Perez-Rodriguez, Steam turbine blade failure analysis, Engineering Failure Analysis, 15 (2008) 129-141.
RkJQdWJsaXNoZXIy MjM0NDE=